Think of life drawing classes and an image of a model sitting on a chair naked for no apparent reason probably pops into your head.

What you probably haven't pictured is the model bent over into the sort of position that would make most gymnasts' eyes water.

But that's exactly what you can expect at Andrew Crayford's life drawing group, The Life Drawing Gymnasia, which sees him and his companions in some pretty impressive athletic and yoga-style postures.

In fact, you might wonder how they stay still long enough for you to draw them.

Models from The Life Drawing Gymnasia have posed for artists at Matthews Yard in Croydon twice already and most recently, this month, they stripped off at Rise Gallery in St George's Walk.

On that occasion Andrew worked with models Natasha Jervis and Jacque Alexis.

Art promoter Leoni Descarte of DescART.es, who curates the art gallery at Matthews Yard, plans to bring The Life Drawing Gymnasia and Andrew, who is from Islington, back to both venues, as well as to The Exchange Workspace, in Scarbrook Road.

You might recognise Andrew as a model from the 2015 BBC1 series The Big Painting. He was also a model for two programmes about renaissance art at The British Museum.

Or perhaps if you've been browsing bookshops you will know his face from the front cover of the Irvine Welsh novel A Decent Ride.

He has also worked extensively with renowned 3D photographer Scott Eaton and posed for the storyboard of the film Legend of Tarzan.

"Everyone has seen me at some point but they just don't know my name," said the 37-year-old.

Andrew, who has been a life drawing model for 10 years, has turned the artform on its head – sometimes almost literally – with The Life Drawing Gymnasia.

He founded the group more than a year ago.

"Having been a model for a number of years I thought it needed a bit more excitement," he said.

"I have always done very dynamic poses. The artists do really get inspired by it. It takes it to a whole new level. The dynamism in it, the athleticism in it and the stamina in it."

He found stereotypical life drawing to be "all very static".

"It is just a drawing and people sitting there for no reason," he said.

"Why would anyone sit there just sort of naked? What are they doing? I found there is a lack of artistry."

He continued: "Being naked is no big deal. Everyone has sort of seen it. That's not what I get paid for. What we are doing is sort of elevating it and upping the ante.

"Representative of life is what we do."

Andrew is booked nearly every day and goes all over the country.

The sessions at Matthews Yard and Rise Gallery lasted three hours.

In that time there are poses which the models typically hold for five, 10 or 15 minutes.

But there are some which he and his fellow models stay in for far longer and for which serious stamina is needed.

The Croydon sessions have been such a success that artists have demanded more.

"They are just so excited and can't wait for the next one," said Andrew.

"It's not like life drawing – it's like a performance. It's just like nothing else they've seen."

Andrew added: "I did another event last night – it was packed, nearly 200 people. Everyone is 'wow'. They are just watching you. It's rock show modelling, a physical performance.

"It literally blew them away."

The poses between the models may look very intimate but they are just focusing on holding the poses, Andrew added.

"We can't afford to think about anything else," he said.

"There's not any room in your head to think about it. You're just using your body in as expressive a way as possible.

"This is about trying to educate people to move beyond their preconceptions of nudity."

In fact, Andrew said he is so busy concentrating he doesn't even really look at the other models.

"It's quite weird – [I've got] two young models and I can't remember it," he said.

"I'm sure it's the same for them. It's just not really a thing. It really is, 'great, the pose is over'. You can't wait to let go of each other. I have done poses where they are hanging on for dear life."

Andrew doesn't spend hours in a gym to maintain his sculptured physique and impressive stamina.

His modelling work combined with cycling, yoga and what he describes as his own form of resistance training has been enough.

"It's not rocket science," he said. "I never go to a gym. Your own body is a gym. You don't need to do a lot physically. Core strength is what it's about.

"It seems to work. I'm constantly being asked to train people."

We can't all be great artists but maybe after reading all this and looking at the photos you feel inspired to give it a go.

"You have got to be willing to try," said Andrew. "You might as well try it with something quite spectacular that actually ignites the passion. If you go to some evening life drawing group and have some model who might not want to be there it might just switch you off."

He continued: "People feel your kind of energy and they feel your kind of passion. It is all about the artistry.

"I get into my zone. I am just concentrating on maintaining the pose. People see that and they start to see you not just as a body but as a shape."